I found a 99 Kawasaki KX250 I'm considering buying. Will I be happy if I buy it?
 

I have a 01 Yamaha YZ 125. I've had a couple of 125's (A suzuki before the one I have now.) I know that it's all about if people have taken care of a bike when looking at a used bike but I was just wondering if there are any problems they are notorious for... I did some research on them and found mixed reviews. Also, is the couple years of age sacrafice from my Yahaha worth any power gain I might get from the 250? Any suggestions??

The 250 will have tons more torque than your 125. Hondas and Yamahas were considered better Kawasaki's in the late 90's and early 00's.But unless you ride at a competitive level, any modern 250 will be a huge upgrade from your 125. I would say ride it, if it feels good, buy it and enjoy it.